Semantic memory in schizophrenia: association with cell membrane essential fatty acids.
BACKGROUND
Semantic memory and language deficits are associated with schizophrenia. Understanding how these systems operate in this disorder will likely require a multi-factorial model that explains their linkages with cognition and modulation by dopamine. A biological factor that may provide causal convergence for these connections is cell membrane composition and dynamics.


METHODS
N400 is an electrophysiological measure of semantic memory and language that is sensitive to deficits in schizophrenia. Relationships among N400, cognition, dopamine, and cell membrane polyunsaturated fatty acids (PUFAs) were examined for patients tested under medicated (haloperidol only) and unmedicated (placebo) conditions. Relationships between these factors and clinical symptoms were also evaluated. The sample included 37 male schizophrenia inpatients and 34 male normal controls. The N400 priming effect was measured from visual event-related potentials recorded during a semantic priming-lexical decision task, in which semantic association (related versus unrelated words) and presentation rate (Stimulus Onset Asynchrony/SOAs: 350 and 950 ms) were varied.


RESULTS
N400 was associated with cognition (speed, visuoperception, attention) in patients and controls. These relationships were influenced by SOA in both groups, and by pharmacological condition in patients. Levels of total PUFAs and arachidonic acid were associated with N400 in unmedicated patients. Clinical symptoms (paranoia, thought disturbance) were associated with N400, but not with cognition or PUFAs.


CONCLUSIONS
Results suggest cell membrane fatty acids are associated with semantic memory and language in schizophrenia. Findings also suggest a series of linkages that are modulated by dopamine: cell membrane fatty acids are associated with N400 semantic priming; N400 semantic priming is associated with clinical symptoms.
Condray
Ruth
R
Western Psychiatric Institute & Clinic, Department of Psychiatry, University of Pittsburgh School of Medicine, 3811 O'Hara Street, Pittsburgh, PA 15213, United States. condrayr@upmc.edu
Yao
Jeffrey K
JK
Steinhauer
Stuart R
SR
van Kammen
Daniel P
DP
Reddy
Ravinder D
RD
Morrow
Lisa A
LA
D000328:Adult; D001095:Arachidonic Acids / Q000378:metabolism*; D001921:Brain / Q000378:metabolism / Q000473:pathology; D010054:Brief Psychiatric Rating Scale; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004298:Dopamine / Q000378:metabolism*; D004910:Erythrocyte Membrane / Q000378:metabolism*; D005071:Evoked Potentials / Q000502:physiology*; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis* / Q000209:etiology*; D009483:Neuropsychological Tests; D012563:Schizophrenia, Paranoid / Q000097:blood / Q000150:complications / Q000473:pathology; D012660:Semantics; D012720:Severity of Illness Index
D001095:Arachidonic Acids; D004298:Dopamine